Electromagnet



Oct. 31, 1944.

H. AYERS ELECTROMAGNET Filed Nov. 13, 1942 Inventor: :Edgar H. ?1825. Jo a/ 7 7 V y His Attorney Patented Oct. 31, 1944 &361.808

ELECTROMAGNET Edgar ll. Ayer. Sclenectady. N. Y.. slgnor to General Electric Company, a oorporation ot New !ork Application November 13. 1942. Serial No. 465.409

8 Ciims.

My invention relates to electric switches, more particularly to electromagnetically operated switches oi' the type ordinarily known as contactors, and has rior its object simple and rellable means tor preventing operation o! the switch by shocks, and for latching the switch in either its open or closed circuit position.

In carrying out m invention in one form, I provide a resilient mounting for the magnet core member on the panel, which mounting provides in the event of shock for a limited amount oi' movement or the panel toward the magnet core. together with an inertia member or weight which is resiliently secured to the armature and located on the side of the pivot of th armature opposite the armature so as substantially to counterbalance the armature. In addition, I also provide a loose or lost motion connection between the armature and the inertia member consisting of a rigid arm secured to the armature which extends loosely into a slot in the inertia body.

With this arrangement, shocks in a direction tending to move the panel toward the magnet core are initially absorbed by the spring mounting, and any slight pivotal movement of the armature toward its unattracted position is damped by the inertia member so that the armature is quickly returned to its attracted position by the magnet coil and without opening of the switch con tacts operated by the armature.

Shocks in the opposite direction with the armature in its attracted position have substantially no eiiect in producing pivotal movement of the armature toward its unattracted position because o! the substantial balancing of the armature by the inertia member.

I also provide manually operated means for positively latching the switch in either its open or closed positions tor providing normal freedom of movement of the armature for electromagnetic operation. v

For a more complete understanding of my invention. reference should be had' to the accompanying drawing, Fig. 1 o! which is a front elevation view ot an electromagnetically operated contactor embodying my invention; Flg. 2 is a side elevation view of the device shown in Fig. 1 looking at Fig. 1 from the right-hand toward the leit-hand side; Fig. 3 is a iragmentary view in perspective of the device shown in Flgs. 1 and 2 'showing various details oi' construction; while l'ig. 4 is a sectiona view along the line 4-4 of Fle. 1 looking in the direction ot the arrows.

invention in one form as applled to a conventional type of electro-magnetically operated switch or contactor. The device which is mounted on a panel o made of suitable electrically I insuating material, such as slate, comprises a pivot shaft or rod ll having its ends mounted in 'bearings z and Il. Mounted on this pivot ii are three electric contact arms ll, !B and i& which cooperate with suitable stationary contacts secured to the panel io. suitable arc chutes I'l, s and s are provided for the contacts. The shalt is biased as by gravity or by a suitable spring (not shown) to the position shown in Fle. 3 in which the switch contacts il, II and !6 are in their open circuit positions. The shatt is moved from the open circuit position to its closed circuit position by means of an Operating coil 20 provided with a stationary magnet core z and a movable armature 22 secured to the shaft il.

It will be understood that a contactor oi' this type is aii'ected by blows or shocks applied to the supporting panel il in a direction to cause rotation ol the shaft il either from the closed circuit position to the open circuit position, or vice versa.

In accordance with my invention, I provide a resilient or spring mounting tor the magnet core !I on the panel ili. As shown, this mountin comprises helical springs 23 and 24 mounted between the magnet core and the panel whereby the magnet core is held resiliently in spaoed relation with the panel. -For supporting the weight of the magnet core, bolts 25 and 28 are provided passing through suitable holes in the panel and loosely through holes in ilanges 21 and 28 on opposite sides of the magnet core. The nuts on these bolts are turned up so as to draw the magnet core toward the panel in suitable spaced relati'on with the panel and also to suitabiy adjust the force appied :by the springs 23 and 24.

It will be observed that the springs 23 and 24 absorb movement of the panel in a direction to ward the magnet core up to a predetermined amount before any appreciable movement of the magnet core is eflected. It will be understood that such independent movement o! the panel ll is a very sudden movement caused by a shock such that the springs are compressed before the torce transmitted by the springs to the magnet core has time to appreciably move the magnet core. This allowable independent movement ot Rei'erring-to the drawing, I have shown my esthe panel permitted by the space between the magnet core and the panel in a typical device was approximately /3 of an inch.

This absorption by the springs of the initiai movement of the panel toward the magnet core prevents the transmission of the initial violence of the Shock not only to the magnet core 2l but also to the armature 22 whereby movement of the armature from its attracted position to its unattracted position is prevented in response to the Shock.

I also provide a weight or inertia member 28 for counterbalancing the armature about the axis of the shaft ll. Thus, as shown, the armature 22 is mounted on the end of a metal plate forming an arm 30 which has its other end secured to a rigid arm 3l and to the shaft l I by suitable bolts. This rigid arm 3 l' extends downward to the side of the shaft ll opposite the armature 22 and extends into a slot 29' in the weight 29, the slot being somewhat wider than the arm and the arm being positioned normally midway of the slot. The arm 3| and slot 29' thus form a loose or lost motion connection between the armature and inertia member. As shown, the weight 29 is mounted on two fiexible spring metal supporting straps or arms 32 and 33 having their upper ends secured to the arm 30 at points adiacent the armature 22.

Any shock applied to the panel II! in a direction perpendicular to the panel Il or any component oi a shock so directed is applied, of course. directly to the supporting bearings of the shaft il and thence to the shaft and to the armature 22 and weight 29. A Shock directed toward the front of the panel, as seen in. Fig. 1, and applied directly through the bolts 25 and 26 to the magnet core 2! thus moves the magnet core with the panel away from the armature 22. In other words, the armature 22, by reason of its inertia, tends to remain stationary and hence as the panel moves away pivots on the shaft ll with respect to the panel. This is assuming, of course, that the armature isin its attracted position, the coil being energized. However, the weight 29 has sufficient weight to counterbalance the armature 22 and the other parts connected to the shaft li so that these parts are substantially balanced about the axis of the shaft. consequently, such a shock applied to the front of the panel o does not cause any relative rotation of the shaft because of the balanced parts.

When the shock is in the opposite direction, i. e., from the back toward the front, or from left to right as seen in Fig. 4, both the springs 23 and 24 and the weight 29 are requ red in the event of an extremely violent shock to prevent movement of the armature 22 to its unattracted position. such a shock may, of course, be a secondary Shock from one initially applied directly to the front ofthe panel. During the Shock after substantial compression of the springs 22 and 24, the magnet core 2i and its armature are forced toward the right, as seen in Fig. 4. This, it will be understood, is a shock applied from the panel n through the springs to the magnet core, as distinguished from the shock applied from the panel to the supporting shaft li. This iatter shock applied to the shaft does not result in any substantial tendency for the armature to move to its unattracted position because of the fact that the armature is balanced by the weight 29 about the shaft.

The sudden blow of the shock appiied to the armature 22, however, in a direction toward the right, as seen in Fig. 4, causes it to rotate i a clockwise direction on the shaft l I. Alter a slight cloclwise rotation, the rigid arm 3! engages the left-hand wall of the slot 2" and is brought to rest together with the armature 22 by the inertia member 29. It will be understood that at this time the spring supporting straps 22 and :I are flexed somewhat by the tendency of the weight 29 to remain stat.onary because of its inertia so that the armature moves siightly with relation to the inertia member. When the armature is thus brought to rest by the weight 28 aiter a very slight movement toward its unattracted DO- sition, it is quickly returned to its attrscted position by the electromagnetic force of the mal!- net. This slight movement of the armature is not suflicient to disengage the movable contacts operated by the armature from their stationary contacts and, therefore, the circuits controlled by the switch remain closed throughout the Shock.

Also, I have provided a handle 34 having three positions, a central or intermediate position in a notch 35, as shown in the drawing, in which the normal electromagnetic operation of the device is permitted, an inner extreme position in notch u in which the armature is manually latched in its attracted and hence closed circuit position, and a third outer extreme position in a notch 21 in which the armature is manually latched in its unattracted position. As shown, the handle is on the end of a spring arm having its lower end pivotally mounted on an arm II secured to the front of the panel on a bracket arm 39, the arm 38 extending substantially parallel with the panel in the central position shown. In its inner position in the notch the stop member 40 carried by the handle engages the outer side of a laterally projecting stop arm 4| secured to the front side of the armature thereby to positively hold the armature in its attracted position. When the handle is in the outer notch 31, an inner stop member 42 carried by the handle engages the inner side of the stop 4l and thereby positively holds the armature in its unattracted position. The stops 40 and 42 are spaced apart far enough to provide for normal free movement of the armature and arm 4| between their attracted and unattracted positions when the handle is in the central notch 35 as shown in the drawing.

It will be 'understood that the arm :I is sutficiently flexible laterally to allow the handle to be moved lateraliy out of one slot and into another. Preferably, as shown, the siots each have overhanging sides thereby to secure the handle against lateral displacement out of the slot. The handle is provided with a portion 43 oi reduced width which freely moves between the overhanging sides of the slots. Furthermore, the arm !I is bent toward the right, as seen in Fig. 1, so that its upper end is biased by the spring free of the arm 28 toward the right against the bottom or right-hand wall of the slot in which it happens to be.

While I have shown a particular embodiment of my invention, it will be understood, of course, that I do not wish to be limited thereto since many modiflcations may be made, and I thereiore contempiate by the appended claimsto cover any such modiilcations as fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. An electromagnet comprising a support, a magnet core member mounted on said support, an Operating coii on said core member, an armature for said core member mounted for moveasomos ment toward and away from said core member,

an inertia member mounted on said armature for movement with relation to said armature in re. sponse to a shock, and a lost motion connection between said armature and said inertia member whereby said inertia member damps movement of said armature in response to a shock.

' 2. An electromagnet comprising a support, a magnet core member mounted on said support, an Operating coil on said core member, an armature for said core member, an arm supporting said armature for pivotal movement about a predetermined pivot toward and away from said core member respectively to attracted'and unattracted positions, a flexible member on said armature extending to the side of said pivot opposite said armature. an inertia membermounted on said flexible member on the side of -said pivot opposite said armature thereby to balance substantialy said armature about said pivot, a rigid member secured to said armature and mounted for movement on said pivot, and a connection between said rigid member and said inertia member providing for limited freedom of movement of said rigid member with respect to said inertia member.

3. An electromagnet comprising a support, a magnet core member mounted on said support, an Operating coil on said core member, an armature for said core member pivotally mounted for movement about a predetermined pivot toward and away from said core member, resilient arm means connected to said armature extending to the side of said pivot opposite said armature, an inertia member mounted on said arm means and substantially balancing said armature about said pivot, said inertia member being provided with a slot, and a rigid member secured to said armature extending loosely 'into said slot and spaced from at least one wall of said slot whereby said inertia member damps pivotai movement of said armature in response to a shock.

4. An electromagnet comprising a support, a magnet core member, a resilient mounting for said core member on said support thereby to provide for movement of said support independently of said core member in response to a shock, an Operating coil on said core member, an armature for said core member mounted for movement toward and away from said core member, an inertia member resiliently mounted on said armature, and a lost motion connection between said armature and said inertia member whereby said inertia member cooperates with said spring mounting to damp movement of said armature away from said core member in response to a shock.

5. An eleetromagnet comprising a support, a

magnet core member. resilient means connecting said core member to said support thereby to provide for movement of the support independently of said core member in response to a shock, an Operating coil on said core member, an armature for said core member, a pivot support for said armature, an inertia member, a spring arm mounting said inertia member on said armature, a rigid arm secured to said armature, and a connection between said rigid arm and said inertia member providing limited freedom of movement of said inertia member with respect to said rigid arm. A

6. An electromagnet comprising a panel support a magnet core member, resilient means connectidt' said core member to said panel thereby to provide for movement of the panel toward said core member independently of said core member in response to a shock applied to said panel after which said panel moves said core member, an Operating coil on said core member, an armature for said core member on the opposite side of said core member from said panel, an arm supporting said armature for pivotal movement about a predetermined pivot toward and away from said core member respectively to attracted and unattracted positions whereby said movement of said core member by said panel in response to a shock moves said armature away from said core member. a flexible arm on said armature extending to the side oi' said pivot opposite said armature. an inertia member mounted on said flexible arm, a rigid member secured to said armature, and a connection between said rigid member and said inertia member providing for limited freedom of movement oi' said inertia member with respect to said rigid member whereby said inertia member damps said movement of said armature away from said core member in response to a shock.

7. An electromagnet comprising a panel support, a magnet core member, means mounting said core member on said panel for limited movement toward and away from said panel. spring means for normally holding said core member in a predetermined spaced relation with said panel thereby to provide for a predetermined limited movement of said panel toward said core member independently of' said core member in response to a shock applied to said panel after which said panel moves said core member, said core member being provided with a plurality of core iegs extending away from said panel and terminating in pole faces substantially paralle with said panel, an Operating coil on said core member, an armature for said core member, means mounting said armature for movement wward said pole faces to an attracted position and away from said pole faces to an unattracted position whereby said movement of said core member by said panel in response to a shock moves said armature away from said pole faces, a spring arm secured to said armature and extending to the side of said shaft opposite said armature, and an inertia member mounted on said spring arm for damping said movement of said armature away from said pole faces in response to a shock thereby cooperating with said spring means to prevent substantial movement of said armature toward said unattracted position in response to a shock.

8. An electromagnet comprising a panel support, a magnet core member, means mounting said core member on said panel for limited movement toward and away from said panel, spring i means for normally holding said core member in a predetermined spaced relation with said panel thereby to provide for a predetermined limited movement of said panel toward said core member independently of said core member in response to a shock applied to said panel after which said panel moves said core member, said core member being provided with a plurality of core legs extending away from said panel and terminating in pole faces substantially parallel with said panel, an Operating coil on said core member, an armature for said core member, an operating shaft supporting said armature for pivotal movement toward said core member to an attracted position in engagement with said pole faces and away from said core member to an unattracted position whereby said movement of said core member by said panel in response ip ecured tanja hft extendin town-d id in- Shock moves said armature awy !rom id pole arti& member into said :lot o u normuy to be faces, s. spring arm secured to said armature md O in pced reton with ai'. lem one wl oi' said extending to the side of said :baft opposite id lot &nd enucin said wll to dmp said movearmature, an i'ertia member mounted on id I ment ot said u 'm ture away from said pole hee: spring arm and substantialy balncing id u. in to I. hock app ed to id panel. mature about said pivot shut, said inertia member being provided with ot, nd a rim rm IDGAR H. AYERB. 

